Palynological constraints on the provenance and stratigraphic range of a Lopingian (Late Permian) inter-extinction floral lagerstätte from the Xuanwei Formation, Guizhou Province, China

Abstract

Late Permian (Lopingian) volcanoclastic lithologies from the Huopu Mine near Fuyuan, Guzihou Province, SW China have yielded konservat lagerstätte-grade plant macrofossils. These fossils derive from a stratigraphic interval bounded by the mid-Capitanian extinction below and the end Permian extinction above and globally, few anatomically preserved floras are known from this age. Due to practical constraints of active mining at the site, to date this konservat lagerstätte is only known from ex situ mine spoil. However, through the use of combined petrographic and palynologic analyses it has been possible to constrain the stratigraphic position, provenance and taphonomic history of these fossils, such that they are now known to have been deposited in in a shallow marine setting as part of the lower member of the Xuanwei Formation during the Wuchiapingian. The palynological assemblage is of low abundance and diversity and is dominated by fern spores with less common lycopsid and sphenopsid spores and gymnosperm pollen, and rare marine acritarchs and is suggestive of an ecologically pioneering rather than established flora. Given the Wuchiapingian age of the lagerstätte this flora has broader potential significance in that affords insights into pre-adaption and resilience to the profound environmental perturbations associated with the mid-Capitanian and end-Permian extinctions, which were key to long term survival into the Triassic.